Ball joint

ABSTRACT

IN A BALL JOINT, THE BEARING FOR THE BALL-LIKE ELEMENT COMPRISES A SUPPORT PORTION OF A LUBRICANT-RESISTANT, ELASTICALLY DEFORMABLE RUBBERLIKE MATERIAL HAVING A SURFACE LAYER FORMED TO COMPLEMENT THE BALL-LIKE MEMBER. THE SURFACE LAYER IS OF A WEAR-AND LUBRICANT-RESISTANT SYNTHETIC RESIN HAVING A LOW COEFFICIENT OF FRICTION, AND IS DEFORMABLE IN CONFORMITY WITH THE UNDERLYING ELASTICALLY DEFORMABLE SUPPORT PORTION. THE SURFACE LAYER HAS AN OPENING OR OPENINGS EXTENDING THERETHROUGH WHICH SERVE AS A RESERVOIR FOR A LUBRICATING OIL AND TO MODERATE OR IMPART FLEXIBLITY TO THE SURFACE LAYER.   D R A W I N G

United States Patent Baba et al.

[ Mar. 7, 1972 [54] BALL JOINT [72] inventors: Takashi Baba; ChiltaraMatsuoka, both of Aichi-ken, Japan [73] Assignee: Toyota Jidosha KogyoKabushiki Kaisha,

Toyota-shi, Aichi-ken, Japan [22] Filed: Sept. 14, 1970 [21] Appl.No.:71,683

Related 0.8. Application Data [63] Continuation-impart of Ser. No.760,849, Sept. 19,

1968, abandoned.

521 u.s.c|. ..287/90R,308/238 5| |m.(:|. ..Fi6cll/06 5g 1 Field ofSearch 287/9011, 87, 85A, 90c; ans/gas 56] References Cited UNITEDSTATES PATENTS 3,236,573 2/i966 Donneiian ..308/238 3,250,554 5/1966Roode ..287/87 2,459,598 1/1949 Stott ..308/238 2,880,025 3/1959Herbenar et al. ..287/85 A Primary Examiner-Andrew V. Kundrat Atrorney-l-iarry G. Shapiro [5 7] ABSTRACT in a ball joint, the bearingfor the ball or ball-like element comprises a support portion of alubricant-resistant, elastically deformable rubberlike material having asurface layer formed to complement the bail-like member. The surfacelayer is of a wearand lubricant-resistant synthetic resin having a lowcoefficient of friction, and is deformable in conformity with theunderlying elastically deformable support portion. The surface layer hasan opening or openings extending therethrough which serve as a reservoirfor a lubricating oil and to moderate or impart flexibility to thesurface layer.

3 Claims, 8 Drawing Figures PATENTEDMAR 7 I972 SHEET 1 [IF 2 FIG. 2

FIG. 4

. INVENIORS TAKASHI BABA 4N0 CHIKARA M ATTORNEY PAIENTEDMAR (I9723,647,249

SHEET 2 UF 2 I INVEN'IORS TAKl-hSl-H 545A AND BY CHIKARA MA SUOKAATTORNEY BALL JOINT This application is a continuation-in-part of ourpending application Ser. No. 760,849; filed Sept. 19, 1968 and nowabandoned.

The invention relates to ball joints and is more particularly directedto improvements in bearings for a ball or ball-like member primarily foruse in the steering linkage and the suspension system of an automobile.

In ball joints, it is desired that there be afforded a predeterminedconstant frictional torque when there is relative motion between thebearing and the ball or ball-like member seated in the bearing. When thesurface portion of a bearing which contacts the ball or ball-like memberis made of metal, it is difficult to maintain uniform or constantdynamic frictional forces with the change of lubricating conditions.Although the contact surfaces of the bearing and the ball are wellfinished, it is practically impossible to obtain uniform contactpressure, particularly where there is sliding friction resulting fromthe relative movement between the ball and the bearing. As a result, itis difficult to obtain constant frictional torque of predetermined valuewhen there is relative motion in rotation or sliding of the parts.

Suitable synthetic resins have been developed for use in bearings.However, synthetic resins are subject to plastic deformation, and it hasbeen difficult to retain the desired or predetermined pressure betweenthe bearing and the adjoining ball, and as a result, it has beendifficult to stabilize or obtain a predetermined constant frictionaltorque. When the bearing is made of rubber, including the surface whichengages or contacts the ball, suitable contact pressure is obtained byvirtue of the elasticity of the rubber. However, a bearing having asurface layer of rubber has its limitations because the frictionaltorque may readily change depending upon lubricating conditions and thepossibilities of abrasion.

An object of this invention is to provide a ball joint frictional torqueof which is constant upon rotation and swing movement.

In accordance with the invention, a ball joint is provided wherein theball or ball-like member is surrounded by a bearing characterized inthat the bearing is mainly composed of a rubberlike or elastomericmaterial, and a wear-resistant synthetic resin having a low coefficientof friction is applied to or embedded therein as a surface layer forcontact with the ball or ball-like member. The surface layer is shapedinto an appropriate form, and preferably has an opening or openingsextended therethrough, so that it may be deformed along with therubberlike material. As a result, the contact pressure between the balland the bearing is stabilized by the elasticity of the rubberlikematerial and the conformity therewith of the overlying wear-resistantsurface layer having a low coefficient of friction. In operation, thesliding movement is between the wear-resistant synthetic resin and theball, and therefore the stability of lubrication and abrasion isexcellent, and a predetermined and in swing movement.

This invention will be described more clearly referring to theillustrative embodiments shown in the attached drawing, in which:

FIG. 1 is a cross-sectional front view of an embodiment of the steeringball joint of this invention;

FIG. 2 is a cross-sectional front view of an embodiment of a suspensionball joint of the invention;

FIG. 3 is a cross section view of a bearing member made in accordancewith the invention;

FIG. 4 is en enlarged cross-sectional view in the planes of line 4-4 ofFIG. 3;

FIG. 5 and FIG. 6 are views similar to FIG. 4, these views illustratingmodifications of the invention;

FIG. 7 is a view similar to FIG. 3, this view showing an embodiment ofthe invention wherein the opening in the surface layer of the bearingmember is in the form of a spiral; and

FIG. 8 is an enlarged cross-sectional view taken in the plane of line8-8 of FIG. 7.

Referring to FIG. 1; 15 is ball or ball-like member; 20 is a socket; 10is a bearing member; 17 is a coil spring. The structure of theassemblage is as follows, i.e., a cylindrical insertion bore 19 isprovided in the socket 20, and the bearing members 10 surrounding theball 15 are inserted into said insertion bore 19, and the stud 14 of theball 15 and the tie rod 21 of the socket 20 are rotatably and tiltablyconnected. The bearing member 10 is formed in such a manner as tosupport a semispherical portion of the ball 15 as is shown in FIG. 4 toFIG. 6 and FIG. 8, and therefore when the ball 15 is provided within thesocket 20, two bearing members, i.e., the upper and lower bearingmembers are provided to surround the ball 15 as a whole. A closure cap18 for sealing the insertion bore 19 is provided on the upper portion ofthe socket 20, a spring seat plate 16 is provided on the upper portionof the upper bearing member 10, and a coil spring 17 is provided betweenthe spring scat plate 16 and the closure cap 18. Resilient pressure isimparted to the contact surfaces of the ball 15 and the bearing members10 by the coil spring 17. Lubricant is placed in the closure cap 18.

Referring to FIG. 2 shows another embodiment of a ball joint for asuspension system, a ball-like member 25 is formed in a semisphericalform, and the semispherical portion is supported by a bearing member 10similar to a bearing member for a ball joint as shown in FIG. 1. Aspring seat plate 26 is provided on the small spherical portion 25aformed on the upper portion of the semispherical portion 25, and thesemispherical portion 25 is pushed down by a coil spring 27 providedbetween the spring seat plate 26 and a closure cap 28. As a result,resilient pressure is imparted to the contact surfaces of thesemispherical portion 25 and the bearing member 10.

Referring to FIGS. 3 and 4, the bearing member 10 comprises a supportportion 11 and surface layer 12 attached or adhered thereto. The supportportion is made or molded of a lubricant-resistant, elasticallydeformable rubberlike or elastomeric material such as an acrylonitrilepolymer or an acrylonitrile-butadiene copolymer. The surface layer isformed to complement the ball or ball-like member, and is made ofwearand lubricant-resistant synthetic resin having a low coefficient offriction. Examples of suitable materials are nylon or a polyamide,teflon or a polytetrafluro-ethylene, and a phenolic resin. The surfacelayer 12 is defonnable in conformity with the underlying elasticallydeformable support portion 11.

The surface layer 12, which contacts the ball 15 or the balllikc member25, lies upon and is adhered to the outer surface 11a of the supportportion 11. The surface layer is provided with an opening which servesto impart flexibility to the surface layer so that it may more readilydeform in conformity with the underlying elastically deformable supportportion. Also, since the outer surface of the surface layer is spacedfrom the outer surface 11a of the support portion, the opening providesa recess adapted to provide a reservoir for a lubricant. In theembodiment of the invention shown in FIGS. 3 and 4, a plurality ofopenings 13 of generally or substantially trapezoidal configurationextend through the surface layer.

In the embodiments of the invention shown in FIGS. 5 and 6, the bearingmembers are designated 40 and 50, respectively. Also, as in the form ofthe invention shown in FIGS. 3 and 4, the surface layers 42 and 52 areprovided with openings 43 and 53 respectively. In the showing of FIG. 5,the surface layer 42 has a portion of its thickness embedded in theouter surface 41a of the support portion 41. With such form of bearingmember a ball or ball-like member will engage the outer surface 42a ofthe surface layer, and will not contact the surface 41a of the supportportion 4]. The openings 43 furnish the dual function of impartingflexibility to the surface layer 42 so that the layer is more readilydeformable with the elastically deformable support portion 41 and therecesses at the openings act to retain a lubricating oil.

In the embodiment of the invention illustrated in FIG. 6, the surfacelayer 52 is embedded in the support portion 51 so that the outer surface51a of the support portion 51 in the areas of openings 53 issubstantially flush or only slightly below the outer surface 52a of thesurface layer 52. The surface 51a does not project above the surface 52aso that the wear is absorbed by the surface layer. Although thisembodiment of the invention furnishes little of the lubricant reservoirfunction, the openings 53 in the surface layer impart flexibility to thelayer for better conformity to the underlying elastically deformablesupport portion.

In the form of the invention illustrated in FIG. 7 and 8, the bearingmember is designated 60, with the support portion and the surface layerhaving the designations 61 and 62, respectively. The surface layer isprovided with an opening in the form of a spiral 63 which extendsthrough the surface layer.

in each of the described embodiments of the invention, the surface layeris molded to the desired semispherical contour and thickness, and withthe described opening or openings extended therethrough. The supportportion is then molded to the preformed surface layer. The mold may beprovided with projections at selected areas to extend into the openingsof the surface layer to limit flow through the openings of the materialwhich will constitute the support portion. Also, the molded surfacelayer may be adhered to a molded support portion by a suitable adhesiveor only set thereon.

In operation, the sliding movement which occurs when there is relativemovement between the bearing and the ball in rotation or in swingingmovement, as indicated by the arrows A and B as shown in FIG. 1, isbetween the surface layer 12 and the ball 15. Due to the construction ofthe bearing member or members as hereinbefore described, the ball jointoperates at a predetermined constant frictional torque in rotation, orin swing movement, or in a combination of such movements. Also, theopening or openings in the surface layer of the bearing member ormembers furnishes a reservoir for a lubricant.

It will be apparent that the surface layer may be provided with anopening or openings having configurations other than as illustrated andhereinbefore described.

The particular configuration of the opening or openings in the surfacelayer selected is determined by the elastic deformation or thestress-reducing property of the materials used for the support portionand the surface layer. When a relatively soft synthetic resin is usedfor the surface layer it is preferred that the openings have the form asillustrated in FIGS. 3, 4, 5 and 6. When a relatively hard syntheticresin composition is used for the surface layer, it is preferred thatthe opening have the shape or configuration as shown in FIGS. 7 and 8.

The advantages and improved results of the invention will be apparentfrom the foregoing description of several preferred embodiments of theinvention. Various changes and modifications may be made withoutdeparting from the spirit and scope of this invention as sought to bedefined in the claims.

We claim:

1. In a ball joint comprising a ball-like member and a bearing membertherefore, the bearing member comprising a support portion of alubricant-resistant, elastically deformable rubberlike material having asurface layer attached thereto, the surface layer being formed tocomplement the hall-like member, said surface layer being of a wearandlubricant-resistant synthetic resin having a low coefficient offriction. the surface layer having at least one opening extendingtherethrough, the surface layer being deformable in conformity with theunderlying support portion.

2. In a balljoint as set forth in claim I, wherein the opening in thesurface layer is spirally formed.

3. In a ball joint as set forth in claim 1, wherein the openingcomprises a plurality of openings each having a substantiallytrapezoidal configuration.

Patent No. d March 79 1972 Date Takashi Baba; Chikara MatsuokaInventor(s) It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 37, after "joint" insert the line 57, after"predetermined" insert constant frictional torque is furnished inrelative rotation line 65, change "cross section" to cross-sectionalline 67, change "en" to an and Column 4, line 29, after "therethrough,insert the outer surface of the surface layer being spaced from thesupport portion to provide a recess at the opening adapted to provide areservoir for a lubricant,

Signed and sealed this 6th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR ROBERT GOTTSCHALK Attesting Officer Commissioner ofPatents FORM F'O-105O (10-69) USCOMM-DC 60376-F59 U.5. GOVERNMENYPRINTING OFFICE 1959 0-356-334

